docs: refocus documentation on browser and self-learning memory

[askadityapandey]

Summary

• refocus public docs on live browser work and self-learning sitemap memory
• remove public adapter and site-plugin authoring pages, with redirects to browser-focused replacements
• preserve established sidebar groups and agent-guide headings while updating their guidance
• correct local versus Cloud setup documentation

Validation

• docs.json parses successfully
• all 22 navigation pages exist
• internal documentation routes resolve
• git diff --check passes

[github-actions]

🟠 Maintainer review suggested — low confidence

The automated review could not reach a fully supported conclusion.

Limitations

• The automated review returned an invalid structured result.

This review is advisory and does not block merging.